Found in a documentation for radio amateurs from the 90s, this circuit is suitable for RF measurements in transmission systems. The potentiometer must be of a special type.
This Motorola circuit uses only one transistor. The circuit is from 1965 documentation. The...
This circuit uses a piezoelectric transducer to produce sounds like a buzzer. Frequency is...
This circuit was suggested by General Electric in a 1965 documentation. The circuit can be...